Photelometer



Aug.1s,1936. C SHEARDETAL l 2,051,317

PHOTELOMETER Filed March ll, 1933 2 Sheets-Sheet 1 Aug. 18, 1936. C, SHEARD E -r AL, 2,051,317

PHOTELOMETER Filed March ll, 1935 2 Sheets-Sheet 2 l i i l mmefazzzxe JUE@ Patented Aug. 18, 1936 PHOTELOlVIETEB.

Charles Sheard,

Dana A.v Rogers,

Application March 11,

s claims.

When a light source of constantintensity is permitted to fall upon a translucent substance,

it will be found that different wave lengths are acteristic curves.

The phenomenon is also useful in problems involving quantitative analysis, color analysis, and in the ascertainment of many other elusive facts;

For the purpose of this disclosure, the invention will be described as applied to a hemoglobinometer, but it'will be distinctly understood that the scope of this invention is not limited to this particular embodiment and illustrative use of thev invention.

Primarily, the

object of this invention is to provide an apparatus and method for obtaining accurate data concerning substances by making use oi their characteristic spectral transmission Other objects of the invention are:

To provide a light and compact apparatus that can be carried easily from place to place; to make it unnecessary to use but a single source of electrical energy for the operation oi' the entire apparatus; to facilitate the taking of readings and cut down the time necessary for making observations and to produce an apparatus which will be extremely accurate and'reliable in operation.

Further and other' objects and advantages will become apparent as the disclosure proceeds and the description is read in conjunction with the accompanying drawings, in which y Fig. l is a. plan view of a preferred embodiment of the invention with parts broken away;

Fig. 2 is a side elevational view of the apparatus shown in Fig.' 1;

- Fig. 3 is a graph showing the light transmission curve of- Oxy-hemoglobin (curve A) and 0f Eastman filter No. 74 (curve B).

Fig. 4 is a fragmentary,longitudinal, sectional view taken on the line il-d of Fig. 1;

Fig. 5 is a sectional view of the cell carrier, the

sectionbeingtaken on the line 5-5 of Fig. 4;'

Fig. 6A is a transverse, sectional view through the lamp' housing, the section being taken on the lline 6 6 of Fig. 4;

Fig. 7 isa d iagrammatic view showing the Arthur H. Sanford, and

Rochester, Minn. 1933, Serial No. 660,400

(o1. ssa-ii) electrical circuit component elerne Since a hemogl an illustrative embodi well to have a clear un upon which it operates. Let a sample of bloo to 12200 with 0.1% sod Auurrlzo"s'ii-irizs PATENT OFFICE/] and the relative position of the nts of the apparatus. obinometer has been chosen as Y ment of the invention, it is derstanding of the theory 5 ium carbonate solution and then thoroughly. shaken with `air to form Oxy-hemoglobin. Then -in a transparent cell so solution is exactly one c intensity is then passe be found, by measuring the spectral transmission c in solution takes the form s Fig. 3.

The eoncen let this d through solution be placed tration of the solution may be determined according to the formula A C 5 loger,

in which C is in solution, AV is the the thickness of the solution, and I of light transmitted. The same' relationship may be expressed by 's hemoglobin or other portional to the ne substance tion of light transmitted.

The constants A an suitable calculation whi line in detail been determined, it is possib here. vWirren F is 'the fraction aying that the concentration of in solution is progative logarithm of the fracd D may be Aobtained by ch is unnecessary to outtheseconstants have le to draw a curve in which the concentration of the substance in solution is plotted ag transmission and from ainst the percentage light this curve readings obtained on the photelometer for percentage light transmission that nay-hemoglobin has sorption bands, and the other a band is usuallyy terme may two

ity to absorb crons, lt is apparent Oxy-hemoglobin ability to' absorb pared 4with some s But to make filter out all band..

solution could this comparison, light outside of the curve'a in Fig. 3

d be taken 'and i ducted Y l that the thickness of the mi 1f light of constant the cell, it will the unabsorbed light, that urve of the substancev hown by curve A inl concentration of the substance absorption ratio, ,D is the be converted immediately into terms of concentration.

It will be observed from characteristic abone occurring at 542 millimicrons t 578 millimlcrons.

d the beta The former that the concentrationof an.

be obtained if its band4 and the l light in this band could b'e oorntandard, 'such as pure water.

it is; necessary to the characteristic Experiments have shownthat the Eastman- Wratten light filter No. 74 manufactured by the Eastman Ko'dak Company of Rochester, New York has a light transmission band which is substantially complementary to the beta\absorption bandv of Oxy-hemoglobin., This* relationship of 4iiltergNo.'14 `to the beta absorption band of oxyhem'o'globin is shown invFig. 3. `Although maximal-transmission in filter No. 74 (seecurve B) occurs vat about 530 millimicrons, whereas the maximal. absorption of the beta band of oxyhemog'lliii'loccurs at 542. millimicrons, the two havebeen found sumciently close'to one another toobtain laccurate results. y

Referring now to Fig. 7, an application of the above principles is diagrammatically illustrated. The reference character I9 designates a constant source of illumination, preferably a 6 volt, 50 candle power incandescent lamp, which is fed from the secondary coil of a constant voltage transformer i2, the primary of which is connected toa suitable source of current, such as the usual 110 volt alternating current line. A transformer which has been found to be satisfactory for delivering constant voltage to the lamp I9 is made by the Sola Electric Company, 2525 Clybourn Avenue, Chicago, Illinois.

The light waves emitted from the lamp |9 are passed successively through `a shutter I3 (shown only in Fig. '1) -an iris diaphragm I4, a condensing lensl I5,4 a cell I6, adapted to contain the specimen under observation, and a light filter I1, preferably Eastman filter No. 74. The unabsorbed light is then allowed to fall upon a light sensitive cell I9, connected in series with a galvanometer I9.

The cell I9 ,consists essentially of a metal disk on which a thin illm of .light sensitive material is deposited. When light falls upon the cell, the metal disk becomes positive, and the film negac tive, so that -when the two are connected by an external circuit, current will flow from one to the other. The strength of the current within certain limits is proportional to the density of the luminous flux, and is capable of measurement by the galvanometer I9, without the use of supplemental batteries, kor other additional electromotive force'.

A cell of this kind which has been found to be satisfactory is manufactured by the Weston Electrical Instrument -Corporation of Newark, N. J., and is known as the Weston photronic cell. 'Ihe galvanometer I9 is also preferably of their manufacture and is their model No. 440.

'I'he entire apparatus is mounted on an elongated base 29, preferably made of'faluminum. At one end of the base, for convenience termed the rear end, there is provided a klamp heusing 2| in which the lamp I9 is adjustably mountl ed: and at the other or forward end of lthe base,

a box-like enclosure 22 houses the filter I1, 'the light sensitive cell I9 and the galvanometer |9.

Between thelampy housing and the galvanometer enclosure, thereisprovided a cell carrier 23which is adapted to removably support the cells containing the specimens under test.

The lamp housing 2| is supported on the base 29 by a tubularpillar-24 provided with front and rear openings 25 and 25, respectively, which permit a circulation ofair .through the and .29 in the lamp housing bodyj29. The lamp I9 which is adiustably positioned in the path of. the current of air is thereby maintained relysleeive 99 projects openings 21 telescopes within the housing body 29 and is provided with a plurality of circumferential open- 5' ings 3|. The rear end of thesleeve 39 is closed lby a; disk 32 preferably of brass which has ran'- enlarged opening 33 receiving the stud 34 which supports the lamp.

The stud 34 is threaded into lthe reinforced base of a socket member 35, and extends rearwardly through the Iopening 33 where it receives a nut 39 which seats upon a washer 31. The I socket member 35 can be adjusted laterally and vertically within the limits of the size of the opening 33 by unloosening the nut 36 and moving the socket to its desired position. The nut 36 is then tightened to hold the lamp in adjusted position.

A plug 39 of insulating material is threaded 2 into the socket 35 and is provided with a centrally embedded bar 39 of conducting material. The forward end of the bar is recessed, as indicated at 49, to receive a spring 4| and a plunger contact 42 which resiliently engages the base 25. contact 43vof the lamp I9.

A metallic sleeve 44 provided with a crimped flange 45 is slipped over the forward end of the plug 39 and has a bayonet socket 46 for engaging the base of the lamp I9. Behind-the. flange 45 is a shield 41 which is clamped against the flange, by a nut 49 threaded on the rear portion of the sleeve 44. The shell of the lamp is connected through the slee've 44 to aconductor. 49, 35 held in place against the flange 43 by the nut 49. The base contact 43 of the lamp is` connected to a conductor 5| by inserting the terminal 52 of the conductor into'a drilled passage provided in the plug 39 and holding .itin place by a small set screw 53. 4

An annular shield 54 iaalso preferably provided so' that light will not be admitted through the openings 3| in the sleeve 39 and yet will permit a circulation of air longitudinally through the lamp housing. l 45 A screw 55 secured by a nut 59 to the inner upwardly through the lamp f housing and is vadapted to travel in a slot 51 when horizontal adjustment of the lamp I9 is being made. A knurled nut 59 threaded o n the upper ,50 end of the screw 55 holds the two sleeves in adiusted position.

The forward end of the lamp housing 2| lis provided with a sleeve 59 supported by a pair of annuler members `im `ma sl. 4A bracket s2 1e 55 secured by bolts 93 tothe upper portion of the annular member y59 and supports a hood 94 above the opening za m the housing body ze. 'rae sides V of the hood are secured to the housing body by `bolts .55 and are held in proper spaced relation in 60 the housing byv spacer sleeves 59.

The condensing lens I5 is mounted in a sleeve 91 and held in place by a.4 retaining ring 59. .The rearof the'sleeve 91 carries the iris diaphragm I4 lwhich may be similar to those used on cam- 85 eras; It will be particularly noted that the sleeve 59 -does not touch the ring 59 which supports the iris diaphragm so that the-'heat of the lamp housing is not conveyed by metal conduction to the specimen under observation.

The cell carrier 2 3 is carried by a platfolmfll supported at opposite ends by machine screws- 1| which are screwed-inte. corner posts 12 of the galvanometer enclosure 22.` Spacer sleeves-'13 it.:`

` notched as indicated at 81 l are centered with respect 80, a ball 88 'urged rearwardly by a spring 89 and .I6 carried bythe cell carrier.

maintain the platform at a proper distance from the enclosure.A y

A lightproof cell housing 14 is supportedonthe platform 10 and comprises side plates 15 and 16, to the inner faces of which are secured other side plates 11. 'The bottoms of the plates 11 are positioned slightly above the upper face of the platform 10 to provide grooves for the flanged base 18 of the cell carrier 23, as

Fig. 4.

Suitable'openings 19 and 80 are provided in the plate 11 to permit light transmitted through the condensing lens I5 to pass through the cells The top of the roof 8| reinforced by bars transversely of the appahousing is closed' by a 82 and 83 extending ratus. y l A.

The cell carrier is best shown in Fig. 5 and consists of a plurality of partitions 84 mounted on the base 18 and flanked by retaining strips 85 for holdingy the individual cellsv in place. It will be particularly noted that the cell carrier has a tighty fit within the cell housing so that no light from an external source can leak into the apparatus and fall upon the light sensitive cell The forward fiange 86 of the cell carrier is so that when the cells to the openings 19 and enclosed within a'sleeve 90 will resiliently hold the cell carrier in position. The sleeve 90 extends between the rear. wall of the enclosure 22 and the front wall of the platform 10.

In order to steady the iront end of the lamp housing with respect to the rest of the apparatus, an arm 9| is rigidly suspended from the lower part of the annular member 8| and re-l ceives a stud bolt 92 which extends into the platform 10. `A spacer sleeve 93 on the stud. bolt holds the lamp housing an rappropriate distance from the rest of the apparatus.

The enclosure 22 which houses light sensitive cell I8, and galvanometer I9 comprises four corner posts 12-to which side plates 94, and front and rear plates 95 and 96, respectively, are rigidly secured. The top of the housing is provided with a cover 91 having an opening 98 into which a magnifying lens 99 is placed to magnify the reading of the galvanometer I9.

' The scale of the galvanometer is illuminated by a bulb |00 which is connected to the same source 'of electricity as the lamp I0.` It may, of course, be operated from any other source, if desired.

The rear wall 98 of the-housing 22 has an opening IOI whichV is connected to the opening80 of the cell housing by a sleeve |02. Clamped tightly against the rearwall 96 is the filter I1 supported by a holder |.03 and having pieces of felt |04 interposed between the wall 96 and thel holder to prevent light leakage. A ring |05 is soldered or otherwise secured to the front of the filter holder |03 to engage the light sensitive cellv I8. Both filter and cell are clamped In place by nuts |03 which are threaded on bolts |01 engaging a retaining plate |08. i

It is particularly desirable to have the position of thelight sensitive cell I8 adjustable with reference to the rear wall 96 so that filters of different thicknesses and characteristics may be use d for transmitting light waves in given bands.

Suitable switches |09, I|0 are provided in the fro'nt wall 95 of the housing 22 for controlling the galvanometer and lamp circuits, respectively.`

The switch |09 merely short circuits the galvashown particularly inv -beam of light.

the nner n',

norneter from the photo-electric cell whilel the switch I I0 opens and closes the source of currentsupply tothe lamp I0 and indicator lamp |00.

In the operation of the apparatus, distilled -water is placed in one of .the cells` I6 and the switches |09 and jIIIl closed. The cell is then moved into the beam of light, and after allowing the light to fall upon the light sensitive cell for hundredths, will read exactly 100. While this is being done, one of the other cells I6 may be filled with a-specimen containing Oxy-hemoglobin, and as soon as the galvanomet'er has become steady at 100, it can then be quickly moved into the The percentage of light transmission can then be directly read Ion the galvanometer.

For convenience, the two outside cells mounted in the cell carrier are usually used for specimens, while the inner cell always contains distilled water,`so that a check on the accuracy of the apparatus may always be 'obtained by passing the light through the pure water cell and observing if the galvanometer reading is still 100.

' The shutter I3 is sometimes desirable to protect the light sensitive cell I8 by allowing the beam to fall upon the cell only when a reading is to be taken. However, by continual use unless excessive light is allowed to fall upon the'cell.

When other substances besides Oxy-hemoglobin are under observation, such as bilirubin, blood sugar, or any other substance, it is, of course, necessary to employ a filter which has the required light transmission characteristics.

As stated before, the invention is not limited to the illustrative embodiment which has been specificallyv described, vor to the use for which that particular apparatus is intended. The appended claims, are, therefore, to be interpreted broadly except as they may be limited by the prior art.

The "term proportional is used in the'appended claims in its broadest sense, and is intended to include-all forms ofV proportionalities including logarithmic proportions.

What we claim, therefore, is:

l. An apparatus for determining the relative concentration of Oxy-hemoglobin inA a solution, comprising a source of illumination, a condensing lens through which vlight from said source is projected, a cell for containing the Oxy-hemoglobin to be tested, movable to a position acrossl the pathof the rays from said light source, a light sensitive cell for receiving said rays, .a filter having a maximal light transmission band for light waves having a length of approximately 530 millimicrons interposed between said lens and said cell, and means for measuring the cell is not damaged i" solution of the amount of a given substance in a translucent specimen by precise measurement of light transmission factors, said apparatus comprising a constant source of illumination, .a light sensitive cell receiving energy from` the source and converting it directlyinto electrical energy capable of measurement without the use of additional electromotive force, a light filter interposed between the source andthe cell and having a light. transmission band corresponding approximately to a characteristicabsorption band of the given substance inl the specimen whereby when the specimen is placed in the path of-light between' current proportional to the concentration oi' the substance in the specimen, and means for measuring the intensity of said current.

3. In apparatus of the class described, a constant source of illumination, a light sensitive cell receiving energy from the source in the form o! l light waves and converting it directly into elec- 'trical energy capable of measurement without the Vthe amount. of a given Isubstance in a translucent a 4specimenvbythe precise measurement of light trans'rrlissionfactors, said method consisting ln subjecting a specimen to light waves from aconstant source of illumination, illtering out all light waves except those corresponding approximately to a characteristic absorption band of the given substance, and then allowingA the unabsorbed light to fall upon a light sensitive cell capable of converting the light directly into electrical energy which can be measured by a galvanometcr without the use of additional electromotive force.

5. In apparatus of the class described, a constant source of illumination, a condensing lens 4 2,051,311' the source and the cell, the cell will produce a associated with the source, means for the source o! illumination to the focal point oi the lens, a cell`carrier slidabie transversely across the beam projected from the lens, a plurality of cells adapted to be inserted in the carrier so that 6 any one may `be Aexposed tothe beam', means for filtering out all light waves except those corre- I spending approximately. to a characteristic absorption band of the given substance, a light sensltive device on the side 1of the cell remote lfrom w theillumination source adapted to produce, an electrical current proportional to the unabsorbed light passing through the cell, which can be measured by a galvanometer without use of additional electromotive torce, and means for measuring l5 the strength of said current.

6. A method of quantitatively determining the amount of a given substance in a translucent specimen by the precise measurement of light transmission factors which comprises determin- 20 ing the characteristic absorption band or bands of the substance, subjecting a specimen containing said substance to light waves from a constant source of illumination, illtering out all'light waves except those corresponding approximately to one 25 of said bands'of said substance, and then causing the unabsorbed light to iall upon a light sensitive cell capable of converting the light directly into electrical energywhich can be measured by tromotive force.

a galvanometer without the use of additional elec- 30 CHARLES sHEARD.v

ARTHUR H. SANFORD. DANA A. ROG/Elta t 35 

